Abstract 724: Improved Carotid Stenoses Quantification on Novel 4D/3d-Doppler Ultrasonography Indexing to the Common Carotid Artery

Objective: Accuracy of internal carotid artery stenosis (ICAS) quantification depends on the method of stenosis measurement, impacting therapeutic decisions and outcomes. The NASCET-method references the stenotic to the distal ICAS lumen, the ECST-method to the local outer and the common carotid artery (CC) method to the CC-diameter. Direct morphometric stenosis measurement with four-dimensionally guided three-dimensional ultrasonography (4D/3DC-US) demonstrated good validity for the commonly used NASCET-method. The NASCET-definition has clinically relevant drawbacks. Our purpose was to investigate the validity of the ECST- and CC-method. Approach: 4D/3DC-US percent-stenosis measures of 103 stenoses (80 patients) were compared to quantitative catheter angiography and duplex-ultrasonography (DUS) in a blinded fashion. Results: The 4D/3DC-US versus angiography intermethod standard deviation of differences (SDD, n = 103) was lower for the CC (5.7%) compared to the NASCET- (8.1%, p <0.001) and ECST-method (9.1%, p <0.001). Additionally, it was lower than the NASCET angiography interrater SDD of 52 stenoses (SDD 7.2%, p = 0.047) and non-inferior for the ECST-method (p = 0.065). Interobserver analysis of equivalent grading methods showed no differences for the SDDs between angiography and 4D/3DC-US observers (p >0.076). Binary comparison to angiography showed equal Kappa values >0.7 and an accuracy >85% for the NASCET- and CC-method, higher than for the ECST-method. Binary accuracy of ICAS grading did not differ from DUS for all methods. Conclusion: The new 4D/3DC-US CC-method is an accurate and well reproducible alternative to the NASCET- and ECST-method and offers perspectives for clinical application.